Circuit breaker control system



Feb. 28, 1933. BORRE 1,899,553-

GIRCUIT BREAKER CONTROL SYSTEM Filed Sept. 25, 1930 Invent-or:

rnsc Borre,

HisA ttorney.

Patented rat. "28, 1933 :UNITED STATES PATENT OFFICE ERNST BOB-BE, OF COPENHAGEN, DENMARK, ASSIGNOR TO GENERAL ELECTRIC OOM- PANY, A CORPORATION OF NEW YORK CIRCUIT BREAKER CONTROL SYSTEM Application flied September 1980, Serial No. 484,411, and in Germany October 10, 1929.

My invention relates to an improved arrangement for controlling the number of times a circuit breaker may be closed within a predetermined time and particularly to such an arrangement employing a thermal responsive device.

I n order that a sensitive thermal responsi've device of a relatively low thermal capac'ity may be used, ithas been proposed heretofore that the winding of an electrical- 1y heatedthermal device be connected in series with the closing coil of the circuit breaker so that the thermal device is heated by the current through the closing coil of the circuit breaker each time it isclosed. Since the duration of the closing operation varies for different types of circuit breakers and also with different operating conditions, such an arrangement as proposed heretofore re uires different thermal devices for the diderent types of breakers. Also due to the series connection of the thermal device and the closing coil of the circuit breaker, the

voltage impressed across the closing coil is decreased. 7

" One object of the present invention is to provide an arrangement by means of which the above mentioned difficulties are elimi- 'n'ated. The invention consists in connecting the heating winding of the thermal device ina circuit which is independent of the closing coil of the circuit breaker in such a manher that each time the circuit breaker is closed, the thermal device is heated for a definite length of time which is independent of the length of time which it takes the circuit breaker to close. i v

In accordance with the preferred embodiment of my invention, I provide a time relay which is energized simultaneously with the closing coil of the circuit breaker and which closes the heating circuit for the thermal relay and effects the interruption of its own heating circuit and the closing coil circuit. The relay is designed so that after it has been deenergized for a predetermined length of time, it opens the heating circuit and. effects the reestablishment of its own operating circuit and the circuit of'the closmg co1l if the circuit breaker is open. In

from the following description when taken in connection with the accompanying drawing which diagrammatically shows one embodiment of my invention and its scope will be pointed out in the appended claims.

Referring to the accompanying drawing,

1 represents a circuit breaker which is arranged to connect a source of current 2 to a, load circuit 3. The circuit breaker 1 ma be of any suitable type, examples of which are well known in the art. As shown, it is of the well known latched-in type and in cludes a closing coil 4 and a trip coil 5 which .2 is connected in series relation with the source 2 and the load circuit 3 when the circuit breaker 1 is closed. The circuit of the closing coil 4 is arranged to be completed across the source 2 when the circuit breaker is open In the particular embodiment of my inven-- 7 tion shown in the drawing, this result is accomplished by means of a control relay 6 which is arranged to be connected across the source 2 by the auxiliary contacts 7 onv the circuit breaker 1 when it is open.

In order to limit the number of times the circuit breaker can reclose, I provide a suitable thermal relay such as a thermostat 8 which is arranged to be heated each time the circuit breaker closes. As shown in the drawing, the. thermostat 8 is arranged to be connected across the source 2 for a definite length of time each time the circuit breaker is closed. This result is obtained by means of a suitable instantaneous pick-up time delay drop-out relay 9, the operating coil of which is connected in parallel with the closing coil 4 of the circuit breaker 1. The relay 9 also controls the circuit of the control relay 6vso that it cannot be reenergized to reclose the breaker 1 as long as the thermostat 8'is being heated. The thermostat 8 is provided with suitable contacts 11 which, when closed, complete an energizing circuit for a suitable lockout relay 12, the contacts 13 of which are in the circuit of the control relay 6.

The operation of the arrangement shown in the drawing is as follows:

When the circuit breaker 1 is closed and a fault occurs on the load circuit 3, the trip coil 5 becomessuficientlyenergized to effect the opening of the circuit breaker 1 to disconnect the load circuit 8 from the source 2; When, the circuit breaker 1 opens, its auxils iary contacts 7 complete through the contacts 13 of the lockout relay 12 and the normally gizing circuit for the control relay 6. When the control relay 6 closes its contacts 15, they connectthe closing coil 4 of the circuit breakier'I andthe coil of the time relay9 across the ,source 2. The energization of the closing ,lcoil 4 closes the circuit breaker 1 so as to reconnect the source2 to the load circuit 3.

- Theenergization of the time relay -9,etfects the opening of its contacts .14 so as to open lthe abovetraced circuit for the control relay6." The energization of thecontrol relay '9f.also closes its contacts 16 so that the thermostat 8 and an adjustable resistor 17 are connected inseries across the source 2. Since breaker at-the time it recloses, the subsequent opening'of the circuit breaker does not effect the reenergiza-tion of the control relay 6, until after the thermostat 8 has been heated for a predetermined length of time. :4 I d is of apermanent character so that-the circuit -breaker-does not remain closed after each re- ..Ifthe' fault connected to the lead circuit closure, the thermostat 8willbe sufliciently heated after the circuit breaker had opened a predetermined number oftimes to close its contacts-11 and thereby connect the'operating coil of the lookout relay across ,the source 2. The energization of the lockout relay 12 permanently opens the contacts 13 in the V energizingcircuit' for the control relay 6 so that further automatic reclosing of the circuit breaker is prevented until the contacts .i of ,thelockout relay are manually reset.

While I have, in accordance with the patent statutes,shown and described my inventionas applied to a particular system and as embodying various .devlces diagrammatically indicated, changes and modifications will be obvious to those skilled in the art and I, therefore, aim in the appended claims to coverall such changes and modifications as fall within thetrue spirit and :scope of my invention. 7

What Iclaim as new-and desire to secure by Letters Patent. of the United States, is,-

for rendering said closing means is energized to close said circuit operation of said closing means for complet- 111g whlle said circuit breaker is open, a

heating circuit for said electrically heated means'and for maintaining said heating c1rcult completed for a definite time which -1s independent'ofthe reclosing time of the cir cuit breaker. closed contacts 14 of the time relay 9 anener- 2; Incombination, a circuit breaker, electroresponsive means for effecting the closing of said circuit breaker, means for energizing said electroresponsive means, a thermal relay, means controlled by said thermal relay means inoperative to close said circuit breaker, 'and'means for completing while said circuit breakeris open and said electroresponsive means is energized a circuit for said thermalrelay for a definite length oftime which is independent of the reclosing time of the circuit breaker.

3. In combination, a circuit breaker, clos nmmeans therefor lncluding a winding, a

' time relay having .itswinding connected in fthe relay- 9 is of the time delay drop-out 7 type, it ,maintains'the circuit of the control relay 6 ,openand the heating circuit ofthe' thermostat-8 closedfor adefinite time which is independent ofgthe time it requires the circuit breakerto close. Therefore, if the overload is still connected to the circuit parallel with said first mentioned winding,

lay for completing a circuitfor said :thermal-relay, and means controlled said thermal relay for rendering said closing .means inoperative to breaker.

4. In combination, an electric c1rcu1t, a circlose said circuit cuit breaker in said circuit, means 'foropenjing said circuit breaker, means responsive to the opening of said circuit breaker for clos-- 'ing the number ofreclosure's of said circuit breaker including a thermal device and means for effecting when said circuit breaker is .open the heating of said device for a definitelength of time which is independentof .ing each closing operation of said circuit for effecting the energization of said electroresponsive means to close said circuit; breaker, and means for limiting thevnumber ,of reclosures of said circuit breaker including a thermal device, timing means for effecting the heating'of said device for a definite length of time which is independent. of the reclosing time of the circuit breaker and means for effecting the operation of said timing means when said electroresponsive breaker. V

7 ing said circuit breaker, and meansfor limit 6. In combination, an electric circuit, a circuit breaker in said circuit, means for opening said circuit breaker, electroresponsive means for closing said circuit breaker, a

circuit for said electroresponsive means, means for closing said circuit, and means for limiting the number of reclosures of said circuit breaker including a thermal device, a heating circuit for said device, an instantaneous pick-up time delay dropout relay controlling contacts in the circuits of said electroresponsive means and said thermal device whereby said thermal device remains energized for a predetermined time each time said electromagnetic means is energized, and

a winding for said relay connected in parallel with said electroresponsive means.

7. In combination, an electric circuit, a circuit breaker in said circuit, means for opening said circuit breaker, means responsive to the opening of said circuit breaker for effecting the reclosing thereof and means for limiting the number of reclosures including a thermal device, means for heating said device a definite length of time each time said circuit breaker is reclosed and means for preventing a subsequent reclosure of said circuit breaker while said device is being heated.

In witness whereof, I have hereunto set my hand this 2 day of September, 1930.

ERNST BORRE. 

